The present invention relates to an extendable/retractable operational sleeve whose transmission shaft is supported to pass through the operational sleeve. In particular, the invention relates to an extendable/retractable operational sleeve used in a working machine such as a grass trimmer.
In a working machine such as a grass trimmer, in order to adjust a length of the operational sleeve suitable for an operator's work, a movable sleeve portion moved in the axial direction and engaged in a telescopic manner with the main sleeve portion is fixed relative to the main sleeve portion by a joint member, thereby adjusting the length of the overall operational sleeve as desired. A transmission shaft for transmitting a driving force from a motor such as an internal combustion engine disposed at a rear end portion of the main sleeve portion to a working tool such as a cutter blade mounted on a front end portion of the movable sleeve portion is supported by bearings within the main sleeve portion and the movable sleeve portion. A stop member for limiting a drawing or separation of the movable sleeve member is provided for preventing the movable sleeve portion from separating away from the main sleeve portion when the operational sleeve is extended. In such a conventional operational sleeve, the joint portion of the operational sleeve is rather complicated, which causes a disadvantage that manufacturing and assembling require a large amount of work and cost.